When you see Mr. Chau on a random stage, go to that stage to fight him. Defeat him to unlock him as a striker.

Play as Nega-Scott

Successfully complete the game with Kim, Ramona, Scott, and Stills to unlock Nega-Scott.

Hidden money and shortcut

At the start of Level 5: "Halloween Party", move backwards to the door with the stars on it to access a secret Subspace Highway. You will collect money and exit the highway past the halfway point of the level. Note: You can pause the game and select "Return To Map" immediately after collecting all the coins to not skip ahead but still get the extra money. -From: MrStilwater

Mobile's secret house

Get the key in Level 6, and fight some wolverines. Notice the small house in the background with a path. Keep walking along the top of the screen to enter a secret path that leads to Mobile's house. Mobile sells a special training manual for $57.50 that unlocks a special move.

Wallace Wells' secret shop

Go to the shopping district in the Frozen Suburbs. Find the ramp that leads down to an underpass. Go up to the star painted on the rear wall. A cement panel will open, allowing access to a shop that sells expensive powerful items.

Video store items

Pay the $504.25 fine at the video store to unlock the corresponding items for purchase for $4.95. Note: You will have to pay the fine again if you play as a different character.